Heating up the search for hidden weapons | Science News for Students

Heating up the search for hidden weapons

A simple infrared-sensing camera and some fancy software can reveal the presence of a concealed knife or gun
May 25, 2018 — 4:37 pm EST
gun detected in waistband

Using thermal imagery and some sophisticated software, a Maryland teen has developed a system that can detect hidden weapons. Here, it reveals a simulated handgun tucked inside a waistband.

Andrew Karam

PITTSBURGH, Pa. — Shootings in U.S. schools have grabbed attention throughout the past few years. And they seem to be happening more and more frequently. On average, there has been one shooting that has killed or injured someone at a school each week this year. A key to limiting such events, some people argue, is keeping concealed guns out of schools. A student from Maryland has now developed a system to reveal hidden firearms. It should even work with other weapons.

Andrew Karam
Andrew Karam, 17, explains to an Intel ISEF judge how his system works to detect hidden weapons.
Chris Ayers/Society for Science and the Public

Andrew Karam, 17, has paired up a simple camera and a nifty bit of computer software. The junior at Arundel High School in Gambrills, Md., showcased his new system here, last week, at the Intel International Science and Engineering Fair (ISEF). He was among almost 1,800 finalists from 81 nations, regions and territories. They competed for about $5 million is prizes and scholarships. Nearly a third of the finalists took home some award.

Security checkpoints at airports already use weapons detectors. Some use X-rays to spot objects based on their density. That’s the same way hospitals use X-rays to distinguish bones from flesh. Other devices detect weapons by looking for changes in a magnetic field. Those changes are due to the presence of metal objects. Still other systems emit small amounts of radiation and then look for reflections that could betray suspicious objects.

Some schools have begun to use similar technologies, Andrew says. But just as at the airport, these devices are typically deployed at checkpoints that people and bags must pass through. That can turn these checkpoints into bottlenecks, he notes; they slow how quickly students can enter or leave a school. Andrew decided to instead design an entirely different type of weapons detector. It uses a computer program known as a neural network.

Such a computer program works somewhat like the human brain (hence its name). In particular, this software learns by studying examples. So, just as people can be trained to recognize suspicious images in scanning systems at airports, this program can too, the teen says. He trained its software using a toy gun. Images of it were taken with an off-the-shelf camera that can be used with cell phones. His camera cost about $300 and can be used with either iPhones or Android devices. Andrew modified the camera’s images to make a concealed weapon stand out.

Story continues below image.

sweatshirt gun

By looking only at heat-carrying infrared wavelengths and boosting an image’s contrast, concealed weapons that remain unseen in visible wavelengths (left) can be easily detected (right) using sophisticated software.
Andrew Karam

How he did it

He started by programming his software to discard the visible-light components captured by his camera. The software now focused solely on the infrared (heat) wavelengths that the camera picked up. Every object has a temperature and thus emits such radiation. (Infrared radiation has a longer wavelength than visible light.) Critically, Andrew notes, infrared radiation passes through clothing and most other materials.

Next, his software transformed color photos of the toy gun into black-and-white images. This is known as a grayscale conversion. After that, the program boosted the contrast in those images. This exaggerated even small differences in temperature to readily distinguish a concealed weapon from the slightly cooler or warmer materials around it.

Andrew fed hundreds of images of the toy gun into his neural network. Each had been taken from a slightly different angle. In just five hours of computing, the software learned to recognize the gun. This system can even recognize an image of the gun if it is part of a video, says Andrew.

A fraction of a second after the software detects the gun, it can provide an alert. That warning can take many forms. A siren might blare out or lights might flash. The alert might even trigger a door to close. That could prevent someone toting a gun from entering a building or a particular room.

Andrew’s neural network could be similarly trained to recognize other types of weapons, including knives. Deployed at the doors of schools or businesses, this sort of system might help save many lives, the teen says.

Society for Science & the Public created ISEF and has been running it since 1950. (The Society also runs Science News for Students and this blog.) Intel sponsored this year’s competition.

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Power Words

(more about Power Words)

angle     The space (usually measured in degrees) between two intersecting lines or surfaces at or close to the point where they meet.

component     Something that is part of something else (such as pieces that go on an electronic circuit board or ingredients that go into a cookie recipe).

computer program     A set of instructions that a computer uses to perform some analysis or computation. The writing of these instructions is known as computer programming.

density     The measure of how condensed some object is, found by dividing its mass by its volume.

engineering     The field of research that uses math and science to solve practical problems.

high school     A designation for grades nine through 12 in the U.S. system of compulsory public education. High-school graduates may apply to colleges for further, advanced education.

infrared     A type of electromagnetic radiation invisible to the human eye. The name incorporates a Latin term and means “below red.” Infrared light has wavelengths longer than those visible to humans. Other invisible wavelengths include X-rays, radio waves and microwaves. Infrared light tends to record the heat signature of an object or environment.

Intel International Science and Engineering Fair (Intel ISEF)     Initially launched in 1950, this competition is one of three created (and still run) by the Society for Science & the Public. Each year now, approximately 1,800 high school students from more than 80 countries, regions, and territories are awarded the opportunity to showcase their independent research at Intel ISEF and compete for an average of almost $5 million in prizes. 

magnetic field     An area of influence created by certain materials, called magnets, or by the movement of electric charges.

network     A group of interconnected people or things. (v.) The act of connecting with other people who work in a given area or do similar thing (such as artists, business leaders or medical-support groups), often by going to gatherings where such people would be expected, and then chatting them up. (n. networking)

neural network     A computer program designed to work in a way similar to the human brain. The programs can “learn” from examples, just as the brain does.

radiation     (in physics) One of the three major ways that energy is transferred. (The other two are conduction and convection.) In radiation, electromagnetic waves carry energy from one place to another. Unlike conduction and convection, which need material to help transfer the energy, radiation can transfer energy across empty space.

Society for Science & the Public     A nonprofit organization created in 1921 and based in Washington, D.C. Since its founding, the Society has been promoting not only public engagement in scientific research but also the public understanding of science. It created and continues to run three renowned science competitions: the Regeneron Science Talent Search (begun in 1942), the Intel International Science and Engineering Fair (initially launched in 1950) and Broadcom MASTERS (created in 2010). The Society also publishes award-winning journalism: in Science News (launched in 1922) and Science News for Students (created in 2003). Those magazines also host a series of blogs (including Eureka! Lab).

software     The mathematical instructions that direct a computer’s hardware, including its processor, to perform certain operations.

technology     The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.

thermal     Of or relating to heat.

wavelength     The distance between one peak and the next in a series of waves, or the distance between one trough and the next. Visible light — which, like all electromagnetic radiation, travels in waves — includes wavelengths between about 380 nanometers (violet) and about 740 nanometers (red). Radiation with wavelengths shorter than visible light includes gamma rays, X-rays and ultraviolet light. Longer-wavelength radiation includes infrared waves, microwaves and radio waves.

X-ray     A type of radiation analogous to gamma rays, but having somewhat lower energy.


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Further Reading

News media: A.J. Willingham and S. Ahmed. U.S. home to nearly a third of world’s mass shootings. CNN. November 6, 2017.